A treatment session is in the 15 gray range and

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Unformatted text preview: oying mainly protons from synchrotron, cyclotron, or linac accelerators are operational and routinely treating a significant number of patients. While protons are the most widespread form of ion treatment, facilities using carbon ions also exist, as their higher biological effectiveness makes them suitable to treating radioresistant and hypoxic tumors (Schardt, 2007). In treatment centers, magnetic steering systems (Gantries) are employed for multidirectional irradiation of a lying patient. Gantries are costly, large, and massive, with a weight exceeding 100 tons for proton systems, and 500 tons for carbon systems (Enghardt et al., 2011). The use of laser-based accelerators was proposed as an alternative to rf accelerators in proton and ion therapy systems (Bulanov et al., 2002; Bulanov and Khoroshkov, 2002; Fourkal, Li, Xiong et al., 2003; Malka et al., 2004), with potential advantages in terms of compactness and costs. Proposed options range from using laser-driven protons as high quality injectors in a rf accelerator (Antici et al., 2011) to all-optical systems, in which ion beam acceleration takes place in the treatment room itself and ion beam transport and delivery issues are thus minimized (Bulanov et al., 2002). It is recognized that there are significant challenges ahead before laser-driven ion beams meet therapeutic specifications, in terms of maximum energy, energy spectrum, repetition rate, and general reliability, to the levels required by the medical and therapeutic standards, as reviewed by Linz and Alonso (2007), where specific issues are mentioned and a comparison with existing accelerator technologies is made. At present, the ion beam parameters are still far from the requirements and it is clear that an extensive, long term activity will be needed to ascertain if and how laser-driven ion beams may become a 28 The use of energetic protons in radiology was first proposed by Wilson, (1946) and demonstrated by Lawrence (1957). Recent reviews on the state of the art in ion beam therapy are given by ¨ Amaldi and Kraft (2005), Smith (2009), and Schardt, Elsasser, and Schulz-Ertner (2010). Focus on research and possible improvements in therapy with heavy ions is given by Kraft and Kraft (2009). Andrea Macchi, Marco Borghesi, and Matteo Passoni: Ion acceleration by superintense laser-plasma . . . competitive option. Several projects are currently active worldwide to explore the potential of laser-driven proton and ion sources for biomedical applications; see, e.g., Bolton et al. (2010), Borghesi et al. (2011), and Enghardt et al. (2011). In view of future applications, several authors have started to design possible delivery systems, including target chamber and shielding (Ma et al., 2006), particle energy selection, and beam collimation systems to enable operation with the broadband and diverging laser-driven beams (Fourkal, Li, Ding et al., 2003; Nishiuchi et al., 2010b; Hofmann et al., 2011). While currently a relative energy spr...
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This document was uploaded on 09/28/2013.

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